The Luminosity of Population III Star Clusters

Abstract

We analyze the time evolution of the luminosity of a cluster of Population III protostars formed in the early universe. We argue from the Jeans criterion that primordial gas can collapse to form a cluster of first stars that evolve relatively independently of one another (i.e., with negligible gravitational interaction). We model the collapse of individual protostellar clumps using 2+1D nonaxisymmetric numerical hydrodynamics simulations. Each collapse produces a protostar surrounded by a massive disk (i.e., $M_{\mathrm{disk}}/M_{\ast }\gtrsim 0.1$), whose evolution we follow for a further 30--40 kyr. Gravitational instabilities result in the fragmentation and the formation of gravitationally bound clumps within the disk. The accretion of these fragments by the host protostar produces accretion and luminosity bursts on the order of $10^6\,\LSun$. Within the cluster, we show that a simultaneity of such events across several protostellar cluster members can elevate the cluster luminosity to 5--10$\times$ greater than expected, and that the cluster spends $\sim 15\%$ of it's star-forming history at these levels. This enhanced luminosity effect is particularly enabled in clusters of modest size with $\simeq$ 10--20 members. In one such instance, we identify a confluence of burst events that raise the luminosity to nearly $1000\times$ greater than the cluster mean luminosity, resulting in $L > 10^8\,\LSun$. This phenomenon arises solely through the gravitational-instability--driven episodic fragmentation and accretion that characterizes this early stage of protostellar evolution.

arXiv comment10 pages, 7 figures, to appear in MNRAS

References in corpus (55)

• Embedded Clusters in Molecular Clouds
• The Formation of the First Star in the Universe
• The Formation of the First Stars. I. The Primordial Star Forming Cloud
• How small were the first cosmological objects?
• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• Forming the First Stars in the Universe: The Fragmentation of Primordial Gas
• Simulations of Early Structure Formation: Primordial Gas Clouds
• One Hundred First Stars : Protostellar Evolution and the Final Masses
• Reionization of the Universe and the Early Production of Metals
• Thermal and Fragmentation Properties of Star-forming Clouds in Low-metallicity Environments
• Formation of Primordial Stars in a LCDM Universe
• Simulations on a Moving Mesh: The Clustered Formation of Population III Protostars
• Generic Spectrum and Ionization Efficiency of a Heavy Initial Mass Function for the First Stars
• Evolution of Massive Protostars with High Accretion Rates
• The Formation and Fragmentation of Disks around Primordial Protostars
• Protostellar Feedback Halts the Growth of the First Stars in the Universe
• The Burst Mode of Protostellar Accretion
• Protostar Formation in the Early Universe
• The Formation of Population III Binaries from Cosmological Initial Conditions
• Formation of the First Stars by Accretion
• The burst mode of accretion and disk fragmentation in the early embedded stages of star formation
• The first stars: formation of binaries and small multiple systems
• The Origin of Episodic Accretion Bursts in the Early Stages of Star Formation
• Formation of Primordial Protostars
• Magnetic Braking and Protostellar Disk Formation: The Ideal MHD Limit
• Zero-Metallicity Stars and the Effects of the First Stars on Reionization
• Population III stars: hidden or disappeared ?
• Population III star formation in a Lambda CDM universe, I: The effect of formation redshift and environment on protostellar accretion rate
• The First Stars: Mass Growth Under Protostellar Feedback
• Pseudo-viscous modeling of self-gravitating discs and the formation of low mass ratio binaries
• The Formation of the First Stars I. Mass Infall Rates, Accretion Disk Structure and Protostellar Evolution
• The Birth of Molecular Clouds: Formation of Atomic Precursors in Colliding Flows
• The Detectability of the First Stars and Their Cluster Enrichment Signatures
• First Structure Formation: I. Primordial Star Forming Regions in hierarchical models
• The effect of magnetic fields on star cluster formation
• Magnetic Fields in Population III Star Formation
• Recurrent Planet Formation and Intermittent Protostellar Outflows Induced by Episodic Mass Accretion
• Protostellar collapse: radiative and magnetic feedbacks on small scale fragmentation
• Can giant planets form by gravitational fragmentation of discs?
• Mixing Metals in the Early Universe
• Bridging the gap: disk formation in the Class 0 phase with ambipolar diffusion and Ohmic dissipation
• Dependence of Halo Properties on Interaction History, Environment and Cosmology
• Fragmentation of Shocked Flows: Gravity, Turbulence and Cooling
• High-Redshift Supernovae and the Metal-Poor Halo Stars: Signatures of the First Generation of Galaxies
• An analytic column density profile to fit prestellar cores
• Detection of isolated population III stars with the James Webb Space Telescope
• Star Formation in the First Galaxies - II: Clustered Star Formation and the Influence of Metal Line Cooling
• Probing the Dark Ages with the Square Kilometer Array
• Variable Accretion Rates and Fluffy First Stars
• The characteristic stellar mass as a function of redshift
• The Burst Mode of Accretion in Primordial Protostars
• How JWST can measure First Light, Reionization and Galaxy Assembly
• Formation and Collapse of Nonaxisymmetric Protostellar Cores in Planar Magnetic Interstellar Clouds: Formulation of the Problem and Linear Analysis
• Nonlinear Evolution of Gravitational Fragmentation Regulated by Magnetic Fields and Ambipolar Diffusion
• Detecting the First Objects in the Mid-IR with NGST

Cited by in corpus (5)

• Formation of Massive Primordial Stars: Intermittent UV Feedback with Episodic Mass Accretion
• On the existence of accretion-driven bursts in massive star formation
• Formation of primordial supermassive stars by burst accretion
• Characterization of Population III Stars with Stellar Atmosphere and Evolutionary Modeling and Predictions of their Observability with the James Webb Space Telescope
• A search for non-thermal radio emission from jets of massive young stellar objects